INCREASING PINOT NOIR COLOUR DENSITY THROUGH SEQUENTIAL INOCULATION OF FLOCCULENT COMMERCIAL WINE YEAST SPECIES
Vitis vinifera L. cv. Pinot noir can be challenging to manage in the winery as its thin skins require careful handling to ensure sufficient extraction of wine colour to promote colour stability during ageing.1 Literature has shown that fermentation with flocculent yeasts can increase red wine colour density.2 As consumers prefer greater colour density in red wines,3 the development of tools to increase colour density would be useful for the wine industry. This research explored the impact of interspecies sequential inoculation and co-flocculation of commercial yeast on Pinot noir wine colour. Six commercial non-Saccharomyces yeast species and two commercial Saccharomyces cerevisiae strains were assayed based on their sedimentation rates in synthetic grape must, both individually and in combination, to determine flocculation ability. The most flocculent S. cerevisiae and non-Saccharomyces spp. yeast pairings, RC212 + BIODIVA and VL3 + BIODIVA, were used in a 20 L-scale Pinot noir winemaking trial. Ul- traviolet-visible spectrophotometric measurements of wine colour parameters, and sensory evaluation of wine appearance, found that mixed species fermentations produced wines with greater colour density. Total and monomeric anthocyanin concentrations were lower in sequentially-inoculated wines, despite being the main source of young red wine colour. Pigmentation assays indicated a higher adsorption of anthocyanins by BIODIVA than S. cerevisiae, suggesting that greater amounts of cell wall mannoproteins in flocculent yeast may scavenge anthocyanins during fermentation, allowing for their subsequent release from the lees and potential for enhanced formation of copigments. Findings from this research have wide application in the industry to increase red wine colour intensity, particular in thin- skinned red grape varieties.
Issue: OENO Macrowine 2023
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Anthocyanins, Colour density, Pinot noir, Sequential inoculation